This intriguing study shows how easily we underestimate the importance of sleep. Six hours of sleep per night is not enough to be productive, even though many people think it is. What's more, six hours of sleep might be just as bad as not sleeping at all.
The study on sleep deficiency, which was published in the magazine Sleep, limited the sleep of 48 adults between the ages of 21 and 38 years for two weeks to a maximum of four, six or eight hours of sleep per night. One unfortunate participant was even deprived of his sleep for three days in a row.
The test subjects who survived for two weeks with six hours of sleep per night eventually functioned just as bad as those who were forced to remain awake for two days in a row. What's disturbing: those who sleep six hours per night think they do function well. During their time in the lab, the participants were tested every two hours for their cognitive abilities and reflexes, except when they were asleep. They were also tested for their moods and the symptoms they showed at that moment, to determine how sleepy the persons felt.
The test subjects which slept eight hours every night functioned best on average. The test subjects who slept four hours per night functioned a little poorer every day.
The group which slept six hours per day functioned normally for the first ten days. However, in the last days of the experiment, the performance of the test subjects turned out to be just as bad as of those who received no sleep at all. The group that only slept for four hours functioned just as bad, but reached its low point earlier on in the experiment.
The most alarming find, according to Fast Company, is that the group who slept for six hours did not describe its sleepiness as bad or negative, while their cognitive performance decreased perceivably.
The results of the study are mainly interesting because they potentially explain how people deal with their sleep deficiency and how they account for this. People with a sleep deficiency are probably (consciously or subconsciously) in denial about their condition. Sleep deprivation leads to "neurobiological costs", the study warns, "which accumulate over time".